The present invention relates to a resistance-changing function body, a memory element, a manufacturing method therefor, a memory device, a semiconductor device and an electronic equipment.
In recent years, it has been proposed to constitute ultramicro electronic equipment of, for example, a single-electron transistor, a single-electron memory and the like by employing a memory that includes a nanometer-size particle called the nanodot and nanocrystal in a gate insulation film. The memory and electronic equipment of this kind are expected to operate with low power consumption taking advantage of a quantum size effect of Coulomb blockade phenomenon or the like.
FIG. 35 is a view showing a conventional memory that employs particles in its floating gate. This memory is provided with an oxide film 4802 that has a thickness of 2 nm and is formed by thermal oxidation, silicon particles 4803 that have a particle diameter of 5 nm and are formed on the oxide film 4802, an oxide film 4804 formed so as to cover the silicon particles and a polysilicon layer 4805 that serves as a gate electrode on a channel region located between source and drain regions 4806 formed in a p-type silicon substrate 4801.
As a manufacturing method of a memory as shown in FIG. 35, there is proposed a method for depositing amorphous silicon on the silicon thermal oxidation film 4802 by an LPCVD (Low-Pressure Chemical Vapor Deposition) apparatus, thereafter forming the silicon particles 4803 through an annealing process and further depositing the silicon oxide film 4804 on the silicon particles 4803 by a CVD (Chemical Vapor Deposition) method (refer to, for example, Japanese Unexamined Patent Application No. 2000-22005).
As another method for forming particles of the silicon particles 4803 or the like, there are proposed a method for forming crystals on a substrate by using CVD, vapor deposition, MBE (Molecular Beam Epitaxy) or the like and a method for forming a thin film and thereafter using a fine processing technique of photolithography, etching and the like besides the use of LPCVD and annealing. According to the methods described above, the aforementioned particles are formed, and thereafter, an insulator layer like the silicon oxide film 4804 of FIG. 35 is laminated on the particles.
However, it is difficult to integrate the conventional memory, single-electron transistor, single-electron memory and so on since they require very fine processing in order to produce a nanosize dot capable of storing one or several electrons and to detect the flow of several electrons. Moreover, it is required to make the memory or the like have an extremely low temperature in many cases in order to restrain the occurrence of malfunction due to thermal fluctuation. Therefore, the memory and the like, which utilize the Coulomb blockade phenomenon or the like, lack practicability and stay at the experiment level.
Moreover, it is often the case where the aforementioned conventional memory manufacturing method has insufficient surface density of particles and insufficient miniaturization of particle size. As a result, there are the disadvantages that the memory window (hysteresis) becomes narrow, a variation in the density is increased and the data retention characteristic is poor.
In particular, to increase the surface density of the particles by the method of forming the particles by using the CVD, deposition, MBE and so on, the particles can be formed only on one surface through one-time process in order to raise the surface density of the particles, and therefore, a similar process is required to be repeated many times.
Moreover, it is extremely difficult to reduce a the particle size and the distance between particles to the nanometer order at the same time by the method of using the fine processing technique of photolithography, etching and the like after the formation of the thin film.